The present invention relates to a unit comprising an electric motor and a machine driven by the electric motor, preferably a piston pump for anti-lock systems of automotive vehicles, for example, wherein the pistons are adapted to be driven by way of an eccentric and the electric motor is adapted to be separated from the machine for trial run purposes.
German patent application No. 43 15 826 discloses a unit of this type. In this application, the housing of the electric motor accommodates a drive shaft in a first bearing and a second bearing at the other end of the housing. The housing of the machine accommodates a third bearing for the drive shaft which, in turn, carries on its eccentric a fourth bearing by which the pistons of the machine are operated. The second bearing with its outside periphery is arranged in the bearing plate of the electric motor but also extends axially into a bore of the housing of the machine when both components are assembled. This construction renders it possible to operate the electric motor independently of the machine for trial run purposes.
However, the above construction suffers from the disadvantage that apart from the large number of bearings and bearing seats and the shaft design which is complicated due to the eccentric, the radially acting reaction forces which originate from the pistons of the machine must be taken up by the second bearing. The second bearing must have corresponding dimensions which necessitates a large mounting space and entails problems with respect to the narrow air gap between the rotor and stator of the electric motor.
Therefore, an object of the present invention is to improve upon a unit of the type mentioned hereinabove so as to permit a low-cost mounting support of the electric motor and the machine in a space-saving manner and by simple means.